GB2297488A - Trocar obturator guard - Google Patents

Abstract

A trocar guard system comprises a member 4 attached to a guard means 10 which surrounds a cutting means (obturator), the guard being capable of limited axial movement relative to the trocar, between a normal extended position in which the guard effectively covers the piercing tip of the trocar and a retracted position in which the tip is exposed. A spring has two arms 5 and 6. When guard member 4 is slid forward arm 6 adopts natural position in channel 3 acting as stop means to prevent any retrograde movement of guard. To reset the latch a cam is moved causing arm 6 to rise allowing guard to slide thereunder.

Description

GUARDED OBTURATOR FOR A TROCAR SYSTEM The present invention relates to a trocar system A trocar is a medical cutting tool used in laparoscopy.

In laparoscopy a hollow tube or cannula is inserted through the wall of the abdominal cavity of a patient to allow surgical tools to be used within the abdominal cavity. The tools are inserted and withdrawn through the cannula. Any surplus tissue or organ can be withdrawn from the cavity through the cannula. One or more cannulae can be inserted through the abdominal wall according to requirements.

In order to penetrate the abdominal wall, the wall must first be cut and this is accomplished with a trocar. A known trocar is in the form of an elongate shaft supporting at its free end, a head of circular cross-section, which is profiled at its free end portion to form a solid three or four sided pyramid defining three or four cutting edges leading away from the tip. The shaft and head are encased in a retractable guard of plastics material. The guard can be displaced longitudinally of the shaft to expose the head but is spring biased so as to envelop the head once any displacement force is removed.

The cutting head is surrounded by a relatively thick plastic sleeve and thus the diameter of the hole made by the cutting head is substantially less than that of tile cannula to be inserted. This means that fiirther hard pushing is required to force the cannula into the hole with consequent stretching and tearing of the tissue of the abdominal wall.

In operation the trocar is inserted into the cannula until it is free and projects from the forward end. The cannula and trocar are then urged against the abdominal wall. The resistance of the wall acts to displace the guard and so exposes the cutting edges.

The head pierces and cuts the abdominal wall until it emerges from the other side ofthe wall, whereupon with the resistance of the wall removed, the guard is resiliently displaced once again to cover the head so that the head is prevented from damaging any organs within the abdominal cavity. Continued penetration will allow the cannula to enter the abdominal cavity.

It is an object of the present invention to provide a trocar with improved safety, wherein the guard cannot normally be retracted to expose the cutting means and can only be so retracted by a latch system, preferably at the proximal end of the trocar.

According to the present invention there is provided a generally cylindrical trocar for forming a hole in the abdominal wall of the patient - to receive a cannula - comprising cutting means and a support means for the cutting means. A guard mounted on the support means for axial movement between a forward position in which the guard covers the cutting means and a retracted portion in which the cutting means are exposed, and spring means acting between the support means and the guard to bias the guard toward its forward position; wherein stop means are provided on the support means and the guard to prevent movement of the guard from its forward position by a simple latch system but will allow movement of the guard from its forward position when the latch system is placed in the arming position.

Embodiments of the present invention are described below, with reference to the accompanying drawings.

Figure 1 shows the system with the trocar 7 inserted in the cannula 8, and with cutting means 9 guarded by a sliding guard 10 over the trocar.

Figure 2 shows the same system with the cutting means 9 revealed by the retraction of the guard 10 on the trocar.

Figure 3 is a horizontal cross-section view of the operating mechanism of the guard system.

Figure 4 is a horizontal cross-section view of the distal end.

Figure 5 is a series of views showing the operation of the latch mechanism which prevents the guarding mechanism from revealing the cutting means unless the latch mechanism is in the armed position, as shown in Figure 5(a).

The method by which the latch mechanism works is described in conjunction with Figure 5. Figure 5(a) shows a side elevation and a plan view of the system, in which 1 is a support attached to the trocar body 2. in such a manner it is free to rotate.

The trocar body 2 has a machined channel section 3 into which slides a rectangular member 4, which is attached to the guard 10.

A spring is held within the member 1 and takes the form of two arms, 5 and 6. In Figure 5(a) arm 5 has been forced parallel to the axis of the support 1 and pushed into a recess caused by the channel which maintains arm 5 in the position shown.

In Figure 5(b) the member 4 has passed underneath arm 6, pushed underneath arm 5, causing arm 5 to rise and spring into its natural position, resting on the surface of member 2, thereby causing arm 6 to be biased towards the channel section 3.

When member 4 is slid forward, as shown in Figure 5(c), the spring arm 6 adopts a natural position against channel 3.

In that position, any attempt to force member 4 backwards, i.e. to reveal the cutting edge of the trocar, is foiled by member 6 preventing member 4 from moving beyond the guarded position.

In order to reset the device so that the guard 10 can be retracted, a simple cam as shown in fig 5(d) moves arm 5 into position as shown in Figure 5(a), causing arm 6 to rise and thus allowing member 4 to slide under arm 6 and towards the proximal end thereby revealing the cutting means 9.

Claims (9)

1. A generally cylindrical trocar system for forming a hole in the abdominal wall of a patient to receive a cannula, comprising a cutting means, a guard mounted around the trocar which has axial movement between a forward position in which the guard covers the cutting means, and a retracted position in which the cutting means are exposed, and spring means acting between the guard and the trocar to bias the guard towards its forward position, wherein stop means are provided on the guard to prevent axial movement of the guard from its forward position by a latch mechanism placed within the trocar but will allow axial movement of the guard from its forward position when the latch mechanism is maintained in a non-functioning situation by the action of a sprung arm 5 regaining its natural position The action of a spring means, forcing the guard mounted around the trocar forward over the cutting means when the cannula has passed through the abdomen, releases the latch which provides locking means to prevent the guard from taking up a retroactive position.

2. A trocar cannula as set forth in Claim 1 wherein the spring means of providing an obstruction to the movement of the guard to reveal the cutting blade may be provided other than by a biased spring lock system but by a lock system in a side tube and actuated by a helical spring which can be incorporated in the body of a trocar

3. A trocar as claimed in any preceding claim, wherein the support means comprises an elongate rod and a connector, one end of the elongate rod receiving the cutting means, the other end of the elongate rod being received by the connector and being engaged in use by a handle of the trocar.

4. A trocar as in any preceding claim, wherein the cutting means comprises a plurality of laminar blades lying in angularly spaced radial planes and having cutting edges inclined to the axis of the trocar and extending rearwardly and radially outwardly from a common point on the axis of the trocar.

5. A trocar as claimed in any one of Claims 3 and 4, wherein the cutting means comprises two generally triangular laminar blades locked together in a cruciform configuration and extending at right angles to each other and sharing a common apex and a common mid-point of the base.

6. A trocar as claimed in Claim 5, wherein one said triangular blade has a slot extending from the apex towards the base and the other said triangular blade has a slot extending from the base towards the apex so that the blades can be fitted together in a cruciform arrangement.

7. A trocar as claimed in Claim 3 or Claim 4, wherein the cutting means comprises two generally triangular blades, each blade being bent through a right angle about a line extending from the apex to the base, the blades being positioned so that one half of each of said blades is generally aligned with a first plane and the other half of each blade is generally aligned with a second plane extending at right angles to the first plane.

8. A trocar cannula system where the position of an indicator means can give an indication as to whether the system is guarded or unguarded.

9. A trocar system substantially as herein described with reference to the accompanying drawings.